The present invention relates to moldboard plows; and in particular it relates to a multiple section, adjustable width plow.
The current trend in tractors is to provide them with ever increasing amounts of power. Large tractors of this type typically are provided with four wheel drive; and this increased power and traction have greatly expanded the capacity of tractors to pull agricultural implements, such as tillage implements. It is desirable to match the load on a tractor to its power so that the tractor operates more efficiently and fuel is not wasted. Thus, there is a trend toward larger and larger implements.
Another feature which is being offered by more manufacturers of moldboard plows, because it is advantageous to a farmer in the field, is the ability to adjust the cutting width of a moldboard plow, particularly without requiring that the farmer stop the tractor and get off and make a manual adjustment. This type of system is sometimes referred to as an adjustable width plow, and the ability to adjust the width of the plow without having to stop the tractor is sometimes described as being adjustable "on the go". A moldboard plow which is adjustable on the go is described in the Kinzenbaw U.S. Pat. No. 3,817,333, granted June 18, 1974. As indicated in this patent, there are two types of steering with which a plow of this type must be concerned. The first type of steering is conventional, namely, some provision must be made for permitting the plow to follow as closely behind the tractor as possible as the tractor turns a corner or follows a bend. For an extremely long plow, such as a multiple section plow, this steering obviously is important. Further, however, in the case of an adjustable width plow, it is necessary to adjust the steering wheel for all width adjustments, and in this adjustment it may further be required that the wheels be oriented to "toe" in a direction slightly inclined relative to the direction of travel of the vehicle in order to offset draft forces on the plow as it works the ground.
A multiple section adjustable width plow which incorporates both kinds of steering indicated above is disclosed in the Kinzenbaw U.S. Pat. No. 4,036,306, granted July 19, 1977; and the same plow is described with particular emphasis on the steering mechanism and its ability to toe the steering wheel in the Dietrich U.S. Pat. No. 4,049,063, granted Sept. 20, 1977. Another multiple section plow which does not provide for width adjustment is disclosed in the Ward U.S. Pat. No. 3,965,989, granted June 29, 1976.
As plows become larger and larger, some provision is made for permitting the frame to flex so that the system can better follow the contour of the ground to insure uniformity of plowing at the depth at which the system is set. As the power of tractors is increased, the length of the plow may be increased to the point where a large number of bottoms may be accommodated on a single plow. The present plow, for example, may accommodate from 16-21 plow bottoms, and in order to provide good contouring, it is desirable that it be divided into three sections, including a forward section, an intermediate section and a rear section. Obviously, the problems of steering around corners and adjusting the steering system in response to cutting width adjustments while also incorporating toeing to offset lateral draft for width adjustments, increase with the size of the plow.
In summary, the present invention includes a first pair of land wheels adapted to support the frame at a location adjacent the connection between the forward section and the intermediate section. A second pair of land wheels supports the system at a location adjacent the connection between the intermediate section and the rear section. A caster wheel is mounted at the forward end of the front section to run in a previously formed furrow, and a rear caster wheel is mounted to the rear plow section to run in the furrow formed by the last plow unit.
The forward land wheels are steered by a linkage mechanism connected to the tractor drawbar in such a manner that the wheels turn in response to the turning of the tractor and they are also adjusted for proper steering and toeing as the cutting width of the plows is adjusted.
The rear land wheels do not turn in response to the turning of the tractor, but they are adjusted for proper steering and toeing in response to width adjustment.
In normal turns, as the tractor turns, the forward land wheels are turned to follow the tractor, and the plow is pivoted about the rear land wheels, with the tail caster wheel swinging out during turning.
Both the forward land wheels and the rear land wheels are structured to toe out for a wide setting of the plows and to toe inwardly (that is, toward the right when viewing the system from the rear) for a narrow cutting width setting to compensate for the effect of changes in draft as the width of the plow changes. Further, the width adjustment mechanism also increases the distance between the right rear wheel of the tractor and the forward furrow wheel on the plow as the plow width increases to further assist in compensating for changes in horizontal line of draft.
An auxiliary hydraulic cylinder is incorporated into the steering mechanism for each of the land wheels to increase the maneuverability of the system, for example, around trees or fence posts. When these cylinders are actuated by the operator (also without leaving his driver's position), both sets of land wheels are turned clockwise. This is useful, for example, in a sharp left turn because it steers the plow sharply to the right to swing it widely about the turn and avoid any obstacles to the left. The same maneuverability may be achieved if it is desired to make a sharp turn to the right by increasing the cutting width to the widest adjustment. This will cause both land wheels to be rotated counterclockwise (when viewed from the top) and thereby swing the plow widely around the turn. These auxiliary steering mechanisms are operative together with the tractor steering of the forward land wheels.
Other features and advantages will be appreciated from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.